Oil burner head



1968 w. D. DYSART ETAL 3,351,365

OIL BURNER HEAD Filed Aug. 7 1964 2 Sheets-Sheet l E q; IJ

8k m u x UL) H? in:

F'I.l

INVENTORS. WILSON D. DYSART WILLIAM J. ZOLLINGER AT TORNE Y.

1968 'w. D. DYSART ETAL 3,361,365

OIL BURNER HEAD 2 Sheets-Sheet 2 Filed Aug.

INVENTORS.

WILSON o. DYSART BY WILLIAM J. ZOLLINGER ATTORNE;

United States Patent 3,361,365 OIL BURNER HEAD Wilson D. Dysart andWilliam J. Zoliinger, Crystal Lake,

Ill., assignors, by mesne assignments, to Union Gil Company ofCalifornia, Los Angeles, Calif, a corporation of California Filed Aug.7, 1964, Ser. No. 388,250 15 Claims. (Cl. 239-4825) This inventionrelates to burners for hydrocarbons and more specifically relates to anoil burner head of unique configuration whereby efficient combustion isobtained and the noise level during burner operation is lowered.Additionally this invention provides a simplified, easily installed unitwith which existing oil burner assembles may be converted to obtaingreater efficiency and substantial abatement of soot deposits on thefurnace and on burner parts.

It is well appreciated by those skilled in the industry thatconsiderable difficulty has been experienced in providing a burner whichcan operate efiiciently at optimum conditions in a manner which isconducive to peace and quiet normally required in the average dwelling.While it has been possible to an appreciable extent to modify burnerhead assemblies so as to gain maximum combustion efiiciency or heatcontent from the fuel utilized, it has not always been possible toconstruct a highly eflicient apparatus which is mechanically simple indesign, eflicient in operation, and able to perform at a reasonably lownoise level.

While the invention is operable in conjunction with any type ofhydrocarbon fuel such as oil or gas, the description herein will besimplified by reference to the generally understood type of oil burnerusing mechanical atomization.

It is an object of this invention to provide a burner head apparatus inwhich air and fuel may be more efiiciently mixed than has heretoforebeen possible and in which the control and adjustment of the mixturewill present no particular problem.

A further object is that of furnishing a burner head unit which willembody relatively few parts, each individually simple and rugged inconstruction and capable of operating over long periods of time withsubstantial freedom from difiiculties.

Another object of this invention is that of providing an assemblycapable of ready association with prior art oil burners whereby theefiiciency of the oil burner is improved, deposition of soot ismitigated and the noise level under which it operates substantiallyreduced.

Various meritorious features of the invention will become apparent fromthe following description taken in conjunction with the drawings whereinlike numerals refer to like parts throughout the several figures andwherein:

FIGURE 1 is a side elevation, partly in section, diagrammaticallyshowing part of a conventional oil burner assembly embodying theimproved head;

FIGURE 2 is a side elevation showing one part of the combination of theherein disclosed invention that may be utilized in pre-existing oilburners;

FIGURE 3 is an end view of the apparatus depicted in FIGURE 2;

FIGURE 4 is a sectional view taken along 4-4 of FIGURE 2;

FIGURE 5 is a sectional View taken along 5-5 of FIGURE 4.

FIGURE 6 is a sectional view taken along 6-6 of FIGURE 4 and;

FIGURE 7 is a sectional View taken along 7-7 of FIGURE 4.

Basically the novel burner head consists in the comthe line the line theline the line "ice bination of two elements. The first is an annulus orendcone having an outlet end, adapted to be connected to a furnacecombustion chamber, of smaller inside diameter than the inlet end. Theinterior surface is grooved or vaned to impart rotational movement tofluids passing therethrough. A second element or air-shield, anembodiment of the invention by itself, is at least partially disposedwithin the interior of the annulus. This element is a hollow truncatedcone having its largest end extending into the larger inlet end of theannulus. The airshield has a series of tapered slots, similar in shapeto a right triangle with the base of the triangle being adjacent to thesmaller end of the air-shield. Guide means on the exterior surfaceadjacent and coextensive with the slots provide means by which fluidsare introduced into the interior of the air-shield and caused to followa rotational path conforming to that of the fluids passing through theannulus. Means by which the air-shield may be aligned and fastened insubstantially rigid relationship within the annulus completes theapparatus.

Referring specifically to FIGURE 1 wherein the more important elementsof a conventional oil burner head assembly are schematicallyillustrated, the numeral 10 designates the wall of a combustion chamberprovided with aperture 12 into which is placed the oil burner blast tube14 having secured to the end thereof annulus 16. Annulus i6 is acylindrically shaped member having a spirally vaned interior surfacewith vanes 20 extending from the inlet side 22 to the outlet end 24. Theinterior diameter of outlet end 24 of annulus 16 is of somewhat smallerdiameter than the interior diameter of inlet end 22. The annulus may beof cast-iron with the ribbing or vanes an integral part thereof, or,alternatively, grooves may be machined on the interior surface of asmooth cast annulus in order to provide raceways 18 through which fluidsentering the intake end 22 are passed through the interior of theannulus 16 to the outlet end 24 Where by the fluids are given rotationalmovement into combustion zone 26. Disposed inside annulus 16 is hollowair-shield 28 having a truncated conical configuration or being cup-likein appearance with the largest diameter of the air-shield beingsubstantially equal to the smallest diameter of the annulus. Theair-shield is slidably disposed within the annulus with the larger endthereof entering through the larger end of the annulus and movabletoward the smaller end thereof. Air-shield 28 has a number of equallyspaced triangular-shaped slots 30 in the conical wall thereofcommunicating the exterior surface of air-shield 28 to the interior ofannulus 16. The slots or apertures 30 are tangential to the smallestdiameter surface 32 of the airshield and have shapes similar to righttriangles. The greatest Width of the slots is adjacent the smallestdiameter of the air-shield. The slots extend a suflicient distancetowards the largest or flared end of the air-shield and are of such sizeso as to permit a sufficient amount of combustion supporting fluid andfuel to be passed therethrough into the interior of the air-shield foreffective combustion. The tapered slots have a maximum width ofapproximately to /s inch and taper to a point near the flared end of theairshield. The length of the slot may be any size, i.e., coextensivewith the length of the air-shield, and is limited only by air-shieldstructural considerations. That is if either the tapered end or widestend of the tapered slot is too near the largest or smallest end of theair-shield respectively, flexibility and structural weakness will resuitin the air-shield. The size of the slots should preferably allow betweenabout 4% and 30% of the amount of air needed for combustion to flowtherethrough. Thus, where a six louvered air-shield is used inconjunction with an efiicient blower fan, the amount of air passingthrough the louver will be about 24% of the total needed for efficientcombustion whereas this percentage will decrease as the inefliciency ofthe blower fan increases.

Juxtaposed to slots 30 are fluid guide means 34 projecting outwardlyfrom the exterior surface of the airshield. Guide means or fins 34 havea louver configuration substantially corresponding to the contour of theexterior surface of the air-shield so that fluids passing over theexterior surface of the air-shield will pass through slots 30 and enterthe interior of the air-shield in a spiral fashion, the rotation of thefluids being substantially the same as the rotational movement given theair passing through the annulus. The fin or guide means are coextendingin length with the slots and have a proiection height of about to inchwith a preferable height of about inch for the normal domestic burner.

Ordinarily, however, the projection height will generally approach thesame dimension as the greatest width of the slot. Air-shield 28 isfashioned of a relatively thin corrosion resistant metal such asstainless steel of about 14 to 28 gauge and has a substantially smoothinterior and exterior surface except for projecting fins or guides 34.While the slots may be punched out of the air-shield and separatespirally shaped fins or air guide means secured adjacent the slot on theexterior surface of the air-shield, it is preferred to make two cuts inthe air-shield with the subsequent bending out of that portion of theconical wall congruent with the slot to form the louver design asillustrated. It is preferred to space the slots at intervals of about 60around the periphery of the shield but smaller or greater spacing may beused. One end of support means 36, preferably formed of bent metal rodsis secured to the exterior surface of the air-shield as by spot weldingor silver brazing. The other end of supporting members 36 are secured tocoupling 42 adapted to be slidably disposed on nozzle adapter 44 or fuelpipe 46. The supportin members 36 may be of any shape so long as theyare fashioned to provide ample clearance for ignition electrode 38 andatomizing nozzle 40. Sufficient clearance between nozzle 48 and nozzleadapter 44 is provided so that coupling 42 is movable axially thereofthereby allowing air-shield 23 to be freely slidable within end-cone 16.Coupling 42, after setting, is held in fixed position at anypredetermined position by means of set screw 47. Alternatively, andpreferably, the distance between the back end of the air-shield andnozzle orifice fixed and placement of the airshield within the annulusis accomplished by moving the nozzle, nozzle adapter and air-shield as aunitary structure thusly maintaining a pre-selected fixed distancebetween the nozzle orifice and back-end of the air-shield. Although apreferred method has been illustrated, the air-shield may be supportedwithin the annulus by other means, as by supporting means secured to theblast tube, nozzle, oil supply conduit, annulus, etc.

In operation air is forced through blast tube 14, by means not shown,towards the combustion chamber and depending upon the position ofair-shield 28 within annulus 16, a portion of the air necessary forcombustion enters the annulus 16 and passes into combustion zone 26 in aturbulent fashion, rotational movement being given the air by ribs orvanes 20. The amount of air entering the combustion chamber through theannulus will of course depend upon the position of air-shield 28 withinthe annulus. Another portion of the air will impinge upon the exteriorsurface of air-shield 28 and will be diverted, in similar rotationalmanner as the air pass ing through annulus 16, by fins 34 through slotsor apertures 34) into the interior of air-shield 28. Another portion ofair will be admitted through the open back end of air-shield 28 alongwith atomized fuel delivered under pressure through fuel pipe 46 throughatomizing nozzle 40. Packing material 43 and 50 is provided around theblast tube 14 at the combustion chamber wall so that atmospheric air isnot drawn into combustion zone 26 Referring to FIGURE 2, there isdepicted the novel unitary air-shield 28 which may be used inpre-existing burners with or without the type of annulus heretoforedescribed. In this embodiment a different type of supporting structurefor the air-shield is provided. The supporting members 36' in thisinstance are three obliquelybent rods. However, it is to be understoodthat these members may take any configuration so long as they do notinterfere with the nozzle head or ignition electrode of the oil burnerapparatus.

Referring to FIGURE 3 the louver design of the slots or apertures 30 isreadily apparent. While six louvers have been shown 60 apart, theapparatus is not to be so limited in that the benefits of this inventionmay be obtained by using fewer slots although it has been found that sixlouvers provide the necessary combustion efiiciency, cleanliness andnoise level reduction.

Referring to FIGURE 4 it is apparent that each of the fluid guide means34 project outwardly from the exterior surface of the air-shield 28 andhas its greatest projection at the smallest diameter of the air-shieldfinally tapering into the contour of the exterior surface of air-shield28.

The spiral-shape in conformance with the contour of the give theincoming air passing into the interior of the conically shapedair-shield a clockwise or counterclock wise rotational movement.However, if the ribs or vanes of the annulus impart a clockwiserotational movement to the air, the fins 34 of the air-shield 28 shouldlikewise impart a similar movement to the fluids entering into theinterior of the air-shield.

The relative sizes of the end-cone and air-shield will of a coursedepend on the size of ofl burner unit in which they ar to be installed.While reference has been made to the smaller type of unit commonly foundin residential use,

the hereinbefore described apparatus will also find industrial utility.Thus where the invention is to be utilized on a domestic type burnerhaving a 34% inch blast tube with a fuel delivery rate of about 2.5g.p.h., and a fan of adequate size to furnish the necessary amounts ofcombustion air, the end-cone will normally have an exterior diametersuflicient in size to accommodate the blast tube and an outlet interiordiameter of about 2%. The overall length of the annulus will be about 1/2 inches and the ribs or vanes on the interior surface will generallyhave a crest height of about /2 inch and have a pitch of about 5". Theair-shield of 22 gauge stainless steel will have a flared-end exteriordiameter of about 2 /1" with the opposite end having an exteriordiameter of about The conical surface will form about a 45 angle withrespect to a plane normal to the end surfaces of the airshield andshould preferably have at least six louvers 60 apart. The crest heightof each louver measured from the exterior surface of the air-shield willgenerally be about and the length of each louver will generally be about1 the slot or aperture length being about less than the louver length.

In operating an oil-burner employing our improved head the air-shutterwill generally be in the full open position thereby necessitating airflow regulation by placement of the air-shield within the annulus. Theamount of air entering the combustion zone through the annulus or aroundthe outer surface of the air-shield will generally be between 2060% andwill preferably be regulated solely by the placement of the air-shieldwithin the annulus so as to have clean combustion with a minimum ofexcess air. As heretofore pointed out the amount of combustion airentering the combustion zone through the slots in the air-shield willgenerally be between about 430% while about 20-60% will enter the openback-end of the airshield along with atomized fuel. However, the amountof combustion air entering through the open back-end of the air-shieldis ideally about 40% of the total amount of air needed for cleancombustion.

In the average domestic burner the air-shield will be placed about infront of the atomizing nozzle for optimum efiiciency and quietoperation. However, the exact placement of the air-shield will dependupon the type of end-cone in which it is disposed and upon the spraypattern, and orifice opening of the nozzle. The number and size of slotsin the air-shield will also affect placement of the air-shield and willinfluence efliciency to some extent. It has been found that the largerthe slots, within practical ranges, the greater the noise reduction willbe. However, an increase in slot size will tend to promote incompletecombustion and thusly contribute to inefiicient smoke control. Thenumber of slots in the air-shield has been found to directly affectcarbon deposits on the interior surface of the air-shield. A cleanerair-shield interior will be possible by the provision of additionalslots thereby making frequent cleaning unnecessary. A satisfactoryoptimum will generally be reached with the provision of at least sixequally spaced slots in the air-shield. The air-shield thus controls toa certain extent the volume and direction of a part of the combustionair, will rotate the air for better mixing with the fuel and willcontrol early vaporization and combustion of the fuel to provide astable flame. It has been unexpectantly found that the temperature ofthe air-shield of our invention is higher than the conventionalair-shield under identical operating conditions. Thus, any foreignorganic matter which ordinarily would partially block the slots orapertures of the conventional air-shield is effectively burned ofl onthe air-shield of this invention thereby eliminating the necessity offrequent cleaning.

A series of noise-reduction tests was conducted wherein the apparatus ofthis invention was compared to other prior art burner heads. The testprocedure consisted in the placement of a microphone, connected to asoundlevel meter, approximately two feet from the front of an averagefurnace having a gun-type oil burner. The microphone was secured inplace so that the same furnace to microphone distance would bemaintained for the entire series of tests. Each of the hereinafterdescribed burner head assemblies were tested under substantially thesame conditions. That is the burner was operated under like conditionsand smoke level readings taken, prior to noise level recording, toascertain that substantially the same conditions existed for each of thetests. In order to obtain the most practical data, a filter network wasemployed in conjunction with the noise recording instruments so as tofilter out those sounds having frequencies below 200 c.p.s. sincegenerally those sounds having a frequency above 200 c.p.s. are the mostannoying and undesirable in furnace operation. 0

The test apparatus consisted in testing varlous component combinationsof burner heads under the foregoing conditions. Thus, a full vaneend-cone, non-vaned endcone, conventional louver design air-shield, andtapered louver design air-shield were tested in various combinations.The tapered louver air-shield represents the apparatus of this inventionheretofore described. The conventional louver air-shield is one havingthe identical conical configuration of the air-shield of this inventionexcept that the louvers in the airshield are of constant opening widthand not tapered as shown in our apparatus. Another significantdistinction between the louver designs is that the fin or guide of theconventional louver does not follow the contour of the exterior surfaceof the air-shield, and bulges at each end of the slot or aperture so asto form a slight recess in the fin or guide surface. A full vanedend-cone is one whose interior surface has spirally shaped grooves orribs as heretofore described, whereas a nonvaned end cone is one whoseinterior surface is practically smooth. The following table illustratesthe data obtained for the indicated combinations.

Apparatus Vaned Nou- Conven- Tapered Decibels end-cone vaned endtionalairlouver aircone shield shield (a) X X 60 59. 3 60. 4 (d) X X 56. 5

It is thusly seen that combination (b) in the above table, representingour invention, produced that lowest operating noise level. It isnoteworthy that a diflerential of approxim-atetly three decibels isequivalent to about a 50% reduction in noise level. The results ofsimilar tests on at least six different furnaces substantiated the noisereduction capabilities of our apparatus.

While theoretically a stoichiometric amount of air or oxygen need onlybe furnished to realize complete combustion of a fuel, it is necessaryto avoid smoke or soot deposition to provide an additional amount orexcess of air or oxygen because of inefiicient mixing of fuel and air.This additional air is excess combustion air and can be determined byanalyzing flue gases for carbon dioxide. The amount of excess combustion'air influences heating plant efficiency since this additional amount ofair lowers the flame temperature, which reduces the ability ofcombustion product gases to transfer their heat in the heat exchangerportion of the heating plant, and increases the volume of combustionproducts thereby producing inefiicient heat transfer due to a greatervolume of gases passing through the exchanger too rapidly. Thus it isdesirable to keep the amount of excess air to a minimum consistant withlow smoke levels.

A series of tests was conducted in order to ascertain the eflectivenessof our improved burner head assembly. A conventional furnace wasequipped with a gun-type oil burner and various burner head designs weretested under similar conditions and the amount of carbon-dioxide in theflue gases was determined by the use of a C0 analyzer. As previouslymentioned the percentage of CO in the combustion gases determines theamount of excess air present. Each test consisted in operating theburner under identical smoke level conditions as determined by the conventional Bacharach smoke testing technique. The results of these testsare tabulated below.

It is readily apparent that the combination of a tapered louverair-shield and vaned end-cone is conducive to elficient combustion sincethe amount of excess :air is relatively low. While the conventionalair-shield rates slightly lower in this respect, the small increase ineificiency is far outweighed by the attendant increase in noise level.

We have described this invention fully and completely with specialemphasis upon several preferred embodiments of the invention. We wish itto be understood that within the scope of the appended claims thisinvention may be practiced otherwise than as specifically describedherein.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An oil burner head which consists in the combination including:

(a) an annulus having an air inlet-end and an outlet end, the outlet endbeing of smaller diameter than said inlet end;

(b) means on the interior surface of said annulus whereby air passingthrough said annulus is given rotational movement;

(c) a truncated cone-shaped, open ended, hollow airshield, the largerend of which is disposed within said annulus, the diameter of said endbeing substantially equal in diameter to the outlet end of said annulus;

(d) slots in the wall of said air-shield, said slots having theirgreatest width adjacent the smallest diameter of said air-shield; and

(e) fluid guide means on the exterior surface of said air-shieldadjacent said slots to give rotational movement to fluid passing throughsaid slots in the same direction as air passing through said annulus.

2. A burner head in accordance with claim 1 wherein said air-shield isslidably disposed within said annulus and means to substantially rigidlyfix said air-shield within said annulus at a selected point on thelongitudinal axis of said annulus.

3. The burner head in accordance with claim 2 wherein the means on theinterior of said annulus to impart rotational movement to said air arespirally shaped ribs extending from the inlet to the outlet ends of saidannulus.

4. The burner head in accordance with claim 3 wherein said ribs areadapted to give a clock-wise rotational movement to said air as viewedfrom a point in front of and exterior to said outlet end.

5. The burner head in accordance with claim 4 wherein said fluid guidemeans on the exterior surface of said air-shield are projecting, taperedfins, the plane of each fin substantially corresponding to the contourof the exterior surface of said air-shield, and the ends of said finscoincident with the smallest diameter of said air-shield having thegreatest projection height with respect to the exterior surface of saidair-shield.

6. The burner head in accordance with claim 3 wherein said fluid guidemeans on the exterior surface of said air-shield are louvers formed bybending outward from the exterior surface of said air-shield thatportion of the wall of the air-shield congruent with said slots, saidlouvers substantially corresponding to the contour of the exteriorsurface of said air-shield.

7. The burner head in accordance with claim 5 wherein said air-shieldhas six equi-distant louvers.

8. The burner head in accordance with claim 7 wherein said louversextend substantially from the smallest diameter to the largest diameterof said air-shield.

9. The burner head in accordance with claim 8 wherein said means torigidly fix said air-shield within said annulus are obliquely bentmembers, the oblique short end of said member being fastened to theexterior surface of said airshield and the other end being connected toa coupling fashioned to be slidably disposed on the oil supply conduitof the oil burner, and means to secure said coupling to said conduit.

10. The burner head in accordance with claim 9 wherein said annulus andair-shield are disposed adjacent to and forwardly of the atomizingnozzle connected to said oil supply conduit.

' 11. Apparatus for burning hydrocarbon fuel discharged under pressurefrom an atomizing nozzle attached to the end of a fuel supply conduitcomprising a burner head having a hollow annulus with an inlet end andan outlet end, said inlet end adapted to be disposed adjacent to andforwardly of said nozzle, said outlet end adaptedto communicate with acombustion chamber, theinterior.

diameter of said outlet end being of smaller diameter than said inletend, the interior surface of said annulus having spirally shaped groovessuflicient in depth to provide raceways for fluids passing throughtheinterior thereof whereby rotational movement is imparted to said fluids;

a truncated, cone-shaped, open-ended, hollow air-shield, the larger endof which is slidably disposed within said annulus, the diameter of saidend being substantially equal in diameter to the outlet end of saidannulus, said airshield having six equi-distant apertures in the conicalwall thereof, said apertures being of substantially triangular shape,with their greatest width adjacent the smallest diameter of saidair-shield, said apertures being substantially coextensive with thelength of said air-shield; outwardly projecting tapered fins, coincidentwith the exterior contour of said air-shield, on the exterior surface ofsaid airshield formed by bending the conical wall of said airshield,congruent with said apertures, said fins having their greatestprojection height adjacent said nozzle and adapted to give rotationalmovement to fluids passing through the interior of said air-shield inthe same direction as the fluids passing through said annulus; means onthe exterior surface of said air-shield extending and secured to amovable coupling adapted to be rigidly secured on said fuel supplyconduit rearwardly of said nozzle whereby the larger end of saidair-shield may be positioned at any predeterminedpoint within saidannulus forward of said nozzle.

12. An air-shield for use in oil burner heads comprising an open-ended,truncated, cone-shaped cup the larger end of which is adapted to bedisposed within the annulus and forward of the atomizing nozzle of anoil burner, the diameter of said end being substantially equal indiameter to the outlet end of said annulus, said cup having a pluralityof tangential slots in the conical wall thereof, each of said slotsbeing tapered and having a substantially triangular shape, the base ofthe triangle being adjacent the smallest diameter of said cup; taperedfluid guide means on the exterior surface of said cup adjacent saidslots, said guide means projecting away from the exterior surface ofsaid cup and substantially corresponding with the exterior contour ofsaid cup whereby fluids passing over the exterior surface of said cupare introduced into the interior of said cup in rotating turbulentfashion.

13. The air-shield in accordance with claim 12 wherein the size andnumber of said slots are suflicient to furnish at least 5% of the oxygenneeded for efiicient combustion.

14. The apparatus of claim 3 wherein said ribs extend outwardly from theinterior surface of said annulus to the surface of an imaginary cylinderformed by the axial projection of said outlet opening, the outermostprojection of said vanes defining an unobstructed cylindrical passagethe length of said body having a diameter equal to the diameter of saidoutlet opening.

15. The apparatus defined in claim 11 wherein said grooves define ribsextending outwardly from the interior surface of said annulus to thesurface of an imaginary cylinder formed by the axial projection of saidoutlet opening, the outermost projection of said vanes defining anunobstructed cylindrical passage the length of said body having adiameter equal to the diameter of said outlet opening.

References Cited UNITED STATES PATENTS 2,396,867 3/1946 Mason 158-153,211,207 10/1965 Luft 158-76 EVERETT W. KIRBY, Primary Examiner.

